Method and device for drilling holes in ice

ABSTRACT

A method and apparatus for drilling holes in ice by melting the ice at the bottom of a drill hole to form a water reservoir and cooling the wall to re-freeze the upper portion of the water reservoir so that a continuous ice shell is maintained around the drill hole.

United States Patent Horbach, deceased et al. 51 Aug. 1, 1972 [54]METHOD AND DEVICE FOR DRILLING 2,193,219 3/ 1940 Bowie et al. 175/1 7HOLES IN ICE 2,684,669 7/1954 Ostrowski ..l75/1l 2,786,652 3/1957 Wells..l75/213 X [72] f i x 2,931,187 4/1960 Perkins ..17s 17 x k 3,115,19412/1963 Adams ..17s 11 g M" 3,152,651 10/1964 Ross ..17s/11 3,390,7297/1968 Aamot ..l75/l8 X 1 Asslgnw Rite 3,482,640 12/1969 Browning..11s/17 x [22] Filed: Oct. 2, 1969 M [21] Appl. No.: 863,176 PrimaryExaminer-James A. Leppink Assistant Examiner-Richard E. F avreau 30Foreign Application Priority um J 5 9? July 19, 1969 Germany ..P 19 36902.9 [57] ABSTRACT [52] US. Cl ..l75/16, 175/18 A method and apparatusfor drilling holes in ice by [51] Int. Cl. F251: 5/04 melting the ice atthe bottom of a drill hole to form a [58] Field of Search ..l75/l6, 17,ll, 18, 213 water reservoir and cooling the wall to re-freeze the upperportion of the water reservoir so that a continu- [56] References Citedous ice shell is maintained around the drill hole.

AV UNITED STATES PATENTS 13 Claims, 1 Drawing Figure 945,209 l/ 1910Avery ..l75/ l 7 METHOD AND DEVICE FOR DRHLING HOLES IN ICE The presentinvention relates to a method and a device for drilling holes in ice.Drilling in ice is of interest for the exploration of the Arctic andAntarctic ice caps as well as for the exploitation of oil fieldsunderlying these ice caps. Practical experiments have shown that thedrilling methods known to date do not lead to any satisfactory results.In the case of the Rotary Drilling Method, generally applied today,considerable heat is developed in the area of the drill point,

which melts the ice and leads to uncontrollable hol-- lows. Theconsequence of this is that the development of the hole is absolutelyuncontrollable and that uncontrollable melting occurs, which continuesup to the surface of the ice and even jeopardizes the stability of thedrilling derrick anchored in the ice. So far no means is known by whichthese phenomena in Rotary Drilling could be prevented.

in addition to the Rotary Method, only the Percussion Drilling Method isknown so far, in which, with the aid of a rope or a string of drillpipe, a sleeve is driven into the ice by repeated percussion. By thismethod only low drilling rates and comparatively shallow depths can bereached, so that this method is uneconomical and the achievable holedepths, in many cases, are insuflicient. Not lastly because of the greathardness of the ice, it appears impossible that, by this method, betterresults could be achieved in ice than by the Rotary Method dealt withabove.

Accordingly, the basis of the invention is the task of providing an icedrilling method pemii tting the drilling of satisfactory deep holes andwhich in addition is economical.

According to the present invention, this task is accomplished by meltingof ice at the bottom of the hole by heat supply, so that at the bottomof the hole a kind of water reservoir is formed, and by cooling the wallof the hole at a certain distance from the bottom to such a lowtemperature that part of the previously melted ice is frozen again toform an ice shell constituting the confines of the drill hole and thetop of the water reservoir, while redundant melted ice is removed fromthe hole.

By cooling the wall of the hole above the water reser voir being formed,it is ensured that this water reservoir does not expand uncontrollably,but remains confined to the area surrounding the bottom of the hole,whereby a controlled sinking of the floor, and thus a controlleddrilling of the hole is guaranteed. By cooling the wall of the hole andby the freezing of part of the melted ice on the wall it can also beensured that the hole has a smooth wall and a defined inside diameter.Removal of the redundant melted ice from the hole can be effected byhaving it displaced by solid particles, as formed by the necessarydrilling unit, or else by means of compressed air or flushing liquids.

The method which is the subject of the present invention is economicaltoo, for there is no need for complicated rotary equipment, requiringmuch power, for a drill bit and the drill rods carrying the bit, nor forcomplicated suspension means for the rotary drill; furthermore, it is nolonger necessary to replace a bit which has become blunt, as isfrequently required in the case of the Rotary Method, and which alwaysrequires extraction of the whole string of drill rods from the hole. Theequipment required for melting practically does not wear out and thepenetration rate mainly depends only on heat supply and on thepossibility of partly freezing the melted ice, so that comparativelyhigh drilling rates can be achieved. As no strings of rotary drill rodsare needed and since there are no tools, frequently to be replaced, atthe end of the bottom rod, the drill rods required for the method whichis the subject of the present invention may remain in place as a casingof the hole, so that no additional string of casing, narrowing the hole,need be installed either. On the contrary, a hole of any diameter can bedrilled, because the rods need not accommodate any torques, which becomeexcessively high with the Rotary Method, when the working diameter ofthe bit exceeds certain limits. Moreover, for a rotary drilling unit,the drill rods must have a big cross section, in order that it canaccommodate such torques, and, therefore, the strings of rods becomeextremely heavy in the case of great depths, for which reason the holediameters are limited, too. As no such torques are produced by themethod which is the subject of the present invention, the rods may bemade with thin walls, so that larger diameters are possible also fromthe point of view of permissible weight. Nevertheless, when applying themethod which is the subject of the present invention, a mainly verticaldrilling of holes is achieved, because, during the melting of the ice,there do not occur any radial forces which might deflect the rod fromthe vertical direction.

The method which is the subject of the present invention may also beused, when rock is included in the ice, because, on account of themelting of the ice, the rock material sinks with the floor of the hole.If required, it is possible to remove by pressure flushing the solidparticles collecting in the water reservoir, such as particles from rockincluded in the ice.

As mentioned above, the present invention also covers a drilling unitfor using the method which is the subject of the present invention. Thisdrilling unit, justlike known drilling units, has a hollow drill rod,but an annular melting head which can be heated is mounted at the bottomend of the drill rod. Above this melting head, the drill rod is providedwith a cooling device keeping its outside face at a temperature of lessthan 0 centigrade, and with a heat-insulating material on its inside.

The heated annular melting head mounted to the bottom end of the drillrod of this drilling unit melts the ice at the bottom of the drill rod,so that the water reservoir mentioned above is developed in the areasurrounding the melting head. While the drill rod sinks farther down,the melted ice displaced by the drill rod rises within the drill rod andis removed continuously from the top end of the drill rod. The coolingdevice causes ice to form on the circumference of the drill rod at theupper edge of the water reservoir, thus closing and sinking the top ofthe water reservoir at a speed corresponding to the sinking of thereservoirs floor due to the melting of the ice. Thus, a hole developswhich closely encompasses the drill rod and presents a continuous smoothsurface. The weight of the drill rod ensures that the drill rod does notbind in the ice hole, and it would also be possible, if required, toprovide the outside of the drill rod with a suitable sliding face, forinstance with a coat of polytetrafluor ethylene.

- 3 In a further embodiment of thepresent invention, the

meltingheadmaypresentacuttingedgeatitsbottom.

elolss'esitsintherneltinghead.'Iheelectriclinesleading tothese heatingelements maybe min a simplemannerthroughcavitiesofthedrill-rod,which,asthe case'ma'y be, may bedouble-walled. Simple cooling results from arrangement ofcoolingjacketsor coiled at the end ofthe drill rod which arefed with a coolant'throughlinesrun through cavirod, which,asthecasemaybe, maybe I double-walled; I

- lt isconceivable, for' example, to use meansoperatingon'thebssisofthePeltierefiectandthecoolingelementsofwhicharearrangedinthedrillrodsareatobecooled, while the elements giving up heat are located in the area'of themelting head. Since,'due to removal of melted ice by pumping, more iceis melted than melted mustbe frozenagain by the cooling means, it is'necessaryflnspite ofthe coolingofthewall ofthe hole,

- g to supply excess-heat, for which the Joule heat may be used which isproduced in the case of a Peltier arrangement, In' any cue, for thecontrol of melting and freezing, feelers may be arranged at the bottomend of the drill rod,.especially for temperature measuring and formeasuring the expansion of the water reservoir.

In the case of a highly preferred embodimentof the invention, theheat-insulating material fills the drill rod 3 completely, and two pipespreferably arranged concentrically' onefin the other pass through theinsulating material, one'ot' the pipes being used for the introduc- 4albeingarranged head.Abovethisheat-insulaungring8,inspaee9betweenthewallsofdrillrodLther'eisacoolingjscketlowhichpreferablyisofannularformationandwhichisdirectlyincontactwiththeinaideofouterwallllofdrillrodL'Ihiscoolingjacketisdividedbyapartition l2intotwocompartmentsl3andl4arrangedconcentrically'oneinthe otherandcomrmmicatingotherattheir bottoms. ThecoolingjacketsUO) com-u partmentl3borderingontheouterwall 11 ofdrillrod 1 ist'edthroughaline l5with'a-coolant, whichatter pssing through outer compartment l3 runsthrough innercompartment 14, which itleavesthroughlinelo. Lines Hand 16,too, areinstalledinthespacebetweenthetwowallsofdrillrodlandareconnectedtoarefrigeratingmachine,'notshowninthedrawing,whichmaybe'arrangedonthesurfaceoratasuitablepointot'-thedrillrod.

2o The interior ofdrill rod 1 a filled with heat-insulatingmatefiall7,andtwopipesl8andl9placedconcentricallyonewithintheotherandextendingapproximatelydown into meltinghead4arearrangedconcentrically withhollowdrillrodl.

Asshowninthedrawing,theheatsupplytothemeltingheadbymeansofheatingelementficausesawaterreservoirlotodevelopatthebottomendofdrillrodl,th'mreservoirsurrotuxiingmeltinghead4andthebottomendofdrillrodlinacertainareakedundantmeltediceriseswithinpipes18andl9andmayberemovedfromtheupperendsofthesepipes. ltis also possible, by introducingcompressed air for example into outer pipe 19, to press the waterthrough inner I pipe 18 out of hollow drill rod l..The water 5inreservoirlfliscommunicatingwiththewatercontainedindrillrodlthrouglhopeninpflprovidedfor.

this purpose in melting head Expansion water I reservoir 20 is preventedby surtion of compressed air or'of a flushing liquid and the 40roundingdrillrod l-atthe upperedgeofr'eservoirZtlby otherfor; removalofmelted ice and/or solid particles originally included in the ice.

\ "Further detailsandarrangements according present invention will benoted from the detailed and-explanations g'ivenhereinafter on the 5basis'of; an arrangement shownias an example onthefdrawingvlhefeaturesshownonthedrawingormentioned in may be usedindividually or'in any-combination with-each other for other.

menu in accordance with'the'present invention. The

drawing schematically shows a longimdinal section of bottom'end ofadrill rod ofa unit in ac- ,cordance with the present invention,the drillrod being in a hole formed in an ice layer. arrangementshownonthedrawingcomprisesa double-walled hollow drillrod 1 into hole 2intoanicymass3. Atthebottomendofdrillrod 1 there is an annular hollowmelting head 4,;the bottom ofwhich ends in a cutting edge 5through'which it is in v contact with'the bottom of the hole 2. .Cli'ise to the cuttingedges, inside melting head 4, there is trolledrefreezing of-melted ,ice and without anymechanicalforce'b'eing--exerted, a hole iswhich,duetotheabsenceoflateralmechanicalforces,canbedrilledinaverystraightline,andthuswithout 5'0 from adiameterot'whichmaybeselec'tedstwillwithinwide limits, because thefactorsinvolved in other cun'entdrillingmethodsandlimitingtheholediameterareinexistentinthis'case'.Solid'fireservoir 20 may readily beremoved from'thewaterreservoirbypressureflushing,whichisusedinasimilar manneras in RotaryFurthermore, if required, drillrod 1 can be'leftas acasing'inftheholeafter completion of same, althoughthe annuhr ice layer rod 1 formsasmooth casing, which in many -dispensingwithacasinganyway.'lhepomibilityof makingholesofalargediameter,on'theotherhand,is

5 important for introducing petroleum extraction lines, it

to be extracted is very warm, it may be of advantage to leave thedouble-walled drill rod in the holes as a casing and to provide it, allover its length, with cooling means which ensure that the wall of thehole remains frozen and thus keeps its stability, while at least one ofpipes 18 and 19 embedded in insulating material within the drill rod,can be used as a petroleum extraction line.

It is understood that the present invention is not limited to thearrangement presented as an example, but that variations from same arepossible without exceeding the scope of the present invention. Thus itis possible to install the electric lines and the cooling lines as wellas pumping pipe 18 inside drill rod 1 and to dispense with thedouble-wall formation of the drill rod 1. Installation of these lineswithin the drill rod may possibly be of advantage for mountingcouplings. Furthermore, it is possible to provide coiled cooling pipesinstead of a cooling jacket, such coiled cooling pipes being attached tothe inside of the drill rod or to the outside of same. Such coolingpipes may then extend all over the length of the drill rod, possiblyhaving a pitch increasing with height. It is also conceivable to useburner units instead of electric heating elements. Moreover, there is apossibility, as shown on the right half of the drawing, to use insteadof the separate heating and cooling elements or in addition to such, aPeltier arrangement 22, 23 the cooling elements 22 of which are arrangedat the bottom end of drill rod 1 and the heating elements 23 of whichare in the area of melting head 4. Feelers 24 serve to monitor thetemperature in the area of water reservoir 20 and in the melting zoneand/or to measure the expansion of the water reservoir and to controlthe rate of heating and cooling to be provided.

Having thus fully described my invention, what I claim as new and wishto secure by Letters Patent is:

1. Method of drilling a hole in ice comprising melting said ice at thebottom of said hole to form at said bottom of said hole a waterreservoir, cooling the wall of said hole at a certain distance from saidbottom to such a low temperature that part of the previously melted iceis re-frozen to form an ice shell constituting the confines of said holeand the top of said water reservoir, and removing excess melted ice fromsaid hole.

2. Method in accordance with claim 1, characterized by pressure-flushremoval, of solid particles from the water reservoir where they haveaccumulated.

3. Drilling unit for drilling holes in ice comprising a hollow drillrod, an annular melting head adapted to be heated and positioned at thebottom 'end of said drill rod, a cooling means positioned above saidmelting head for keeping the outside face of said drill rod at atemperature of less than 0 centigrade, and a heat insulating materialpositioned on the inside of said hollow drill rod.

4. Drilling unit in accordance with claim 3, characterized by the factthat said melting head has a cutting edge at its bottom end.

5. Drilling unit in accordance with claim 3, characterized by heatinsulation being provided between said melting head and said drill rod.

6. Drilling unit in accordance with claim 3, characterized by the factthat electric heating elements are arranged in said melting head andthat electric lines leading to these heating elements are run throughcavities f od h' d bl o Q ab coe anz evi claim 3, characterized by thefact that, at the bottom end of said drill rod cooling means areprovided which are fed with a coolant through lines, which are runthrough cavities of drill rod which, is doubled-walled.

8. Drilling unit in accordance with claim 3, characterized by the factthat, for heating said melting head i and for cooling drill rod, aPeltier arrangement is used.

9. Drilling unit in accordance with claim 3, characterized by the factthat, at the bottom end of the drill rod, feelers for detecting thepresence of melted ice are arranged.

10. Drilling unit in accordance with claim 3, characterized by the factthat the heat-insulating material completely fills said drill rod andthat two pipes run through it, one of which is used for introducing aflushing fluid and the other for removing melted ice and/or solidparticles of material included in the ice.

11. Drilling unit in accordance with claim 10, characterized by saidpipes being arranged concentrically one in the other.

12. A method of forming a hole in ice having a defined boundarycomprising:

1. melting said ice in the region in which said hole is desired therebyforming a reservoir of water in the vicinity thereof,

2. re-freezing the upper portion of said reservoir of water to form ahole in said ice having said defined boundary, and

3. removing water from said water reservoir in excess of the amountrequired to form, upon re-freezing, said defined boundary.

13. An apparatus for forming a hole in ice comprismg:

l. a hollow drill tube,

2. a melting head means, annularly arranged at the lower end of saidhollow drill tube, for melting said ice,

3. a cooling means, positioned above said melting head means, forcooling the exterior surface of said drill tube to re-freeze the upperportion of the melted ice so that said hollow drill tube is encased bysaid ice,

4. an insulating means, located between said melting head means and saidcooling means, for limiting the conduction of heat therebetween, and

5. a means, operatively arranged in the lower end of said hollow drilltube, for removing melting ice in excess of the amount required to form,upon refreezing, the encasing ice.

1. Method of drilling a hole in ice comprising melting said ice at thebottom of said hole to form at said bottom of said hole a waterreservoir, cooling the wall of said hole at a certain distance from saidbottom to such a low temperature that part of the previously melted iceis re-frozen to form an ice shell constituting the confines of said holeand the top of said water reservoir, and removing excess melted ice fromsaid hole.
 2. Method in accordance with claim 1, characterized bypressure-flush removal, of solid particles from the water reservoirwhere they have accumulated.
 2. a melting head means, annularly arrangedat the lower end of said hollow drill tube, for melting said ice, 2.re-freezing the upper portion of said reservoir of water to form a holein said ice having said defined boundary, and
 3. removing water fromsaid water reservoir in excess of the amount required to form, uponre-freezing, said defined boundary.
 3. a cooling means, positioned abovesaid melting head means, for cooling the exterior surface of said drilltube to re-freeze the upper portion of the melted ice so that saidhollow drill tube is encased by said ice,
 3. Drilling unit for drillingholes in ice comprising a hollow drill rod, an annular melting headadapted to be heated and positioned at the bottom end of said drill rod,a cooling means positioned above said melting head for keeping theoutside face of said drill rod at a temperature of less than 0*centigrade, and a heat insulating material positioned on the inside ofsaid hollow drill rod.
 4. Drilling unit in accordance with claim 3,characterized by the fact that said melting head has a cutting edge atits bottom end.
 4. an insulating means, located between said meltinghead means and said cooling means, for limiting the conduction of heattherebetween, and
 5. a means, operatively arranged in the lower end ofsaid hollow drill tube, for removing melting ice in excess of the amountrequired to form, upon re-freezing, the encasing ice.
 5. Drilling unitin accordance with claim 3, characterized by heat insulation beingprovided between said melting head and said drill rod.
 6. Drilling unitin accordance with claim 3, characterized by the fact that electricheating elements are arranged in said melting head and that electriclines leading to these heating elements are run through cavities of saiddrill rod which is double-walled.
 7. Drilling unit in accordance withclaim 3, characterized by the fact that, at the bottom end of said drillrod cooling means are provided which are fed with a coolant throughlines, which are run through cavities of drill rod which, isdoubled-walled.
 8. Drilling unit in accordance with claim 3,characterized by the fact that, for heating said melting head and forcooling drill rod, a Peltier arrangement is used.
 9. Drilling unit inaccordance with claim 3, characterized by the fact that, at the bottomend of the drill rod, feelers for detecting the presence of melted iceare arranged.
 10. Drilling unit in accordance with claim 3,characterized by the fact that the heat-insulating material completelyfills said drill rod and that two pipes run through it, one of which isused for introducing a flushing fluid and the other for removing meltedice and/or solid particles of material included in the ice.
 11. Drillingunit in accordance with claim 10, characterized by said pipes beingarranged concentrically one in the other.
 12. A method of forming a holein ice having a defined boundary comprising:
 13. An apparatus forforming a hole in ice comprising: